WASHINGTON - Brisk walking three hours a week can cut the risk of heart disease in women by as much as 40 percent, equivalent ot the benefits of regular aerobics, jogging or other vigorous physical activity, according to a new study by Harvard University researchers. The study, the largest of its kind, is the first to show the effectiveness of walking in reducing heart disease risk in women. Only a few studies have examined the effects of walking on the heart and nearly all were conducted on men. The most recent - the Honolulu Heart study of nearly 2,700 elderly men - reported in July that men who walked less than a kilometre a day had twice the heart disease risk of those who walked more than two kilometres per day or more. In the new study, women who walked at about five km/h or more for at least three hours per week achieved the same reduction in heart disease risk as those who engaged in vigorous exercises such as aerobics, jogging or bicycling. "The important caveat is that the heart protection does not apply to casual strolling and window shopping at the mall," said JoAnn Manson, professor of medicine at Brigham and Women's Hospital in Boston and lead author of the study. "We've long known that walking was a great excercise," said former U.S. surgeon-general Everett Koop. "But this study shows the strong health benefit that it can have in protecting women against heart disease."
Experts have long questioned whether walking alone could provide a strenuous enough workout to help prevent premature heart disease. "This study is important because it demonstrates that even moderate levels of excercise, something as simple as walking, can be equally protective against heart disease as more vigorous exercise," said Teri Manolio of the U.S. National Heart, Lung and Blood Institute, which sponsored the study. The study, published in today's New England Journal of Medicine, included 72,488 female nurses, age 40 to 65. All were part of the Nurses' Health Study, a long-term research project that began in 1976, involving nearly 122,000 nurses. Participants in the study filled out questionnaires about their physical activity. They detailed the average amount of time spent jogging, bicycling, hiking, swimming and engaging in other common exercises, such as aerobics. Women who walked briskly at least three hours per week - about 30 minutes per day - had a 30 percent to 40 percent lower risk of suffering a heart attack than sedentary women, the study found. The more women walked, the lower their risk, according to the study. Women who walked briskly five hours per week cut their risk of heart disease in half compared with their more sedentary counterparts. Even women who smoked, were overweight or had other risk factors for heart disease, such as elevated LDL (Low Density Lipids: bad cholesterol, where we need more HDL - High Density Lipids: good cholesterol) blood cholesterol levels, high blood pressure or a family history of premature heart disease significantly reduced their risk of premature heart disease by regular, brisk walking, the study found. Walking apears to cut the risk of heart disease by reducing blood pressure, blood sugar and LDL blood cholesterol levels. It also improves insulin sensitivity and reduces blood clot formation.